Charger/gen head efficiency?

[mbryner]

the output would have to be fed to a mppt controller rather than a more common pwm solar controller

Hee hee.   This thread makes me want to run some percent efficiency measurments on my system.  Bob, you forgot to mention besides the losses from the generator itself there losses from a step down transformer and from the charge controller, too.

....in theory it could do nearly 70amps

I run at 40 amps charging and I could get up to 80 amps if the prime mover would handle it.   Alas, a 6/1 will not.

however the mppt controller is going to cost more than the generator, the rectifier, and all the other stuff needed to connect it all together
probably by a factor of 2 or more.

Exactly.   If you're doing any kind of home-brew AC gen to DC battery charging, any mppt controllers that can handle for example V peak of 250 V or greater (after rectified to DC) are super-duper expensive.  (Thinking of the new Midnight Solar Classic.)   And try finding a heavy duty charge controller off the shelf that can handle decent charge amperage.

When all is said and done, how much more efficient is AC gen than DC?  Probably not much.   I'm doing it for convenience and not having to switch out gen heads.

[BioHazard]

So...to summarize...is there no "reasonable" way I can take, say, 700watts from my little 120v generator, and put it completely or nearly so into a 12v battery?

These guys claim that charging with an automotive type alternator is more efficient than using an AC generator coupled to a charger.

What kind of engine is this?

[Lloyd]

Hi Bio,

Not with any real efficiency.

That ample power genie is a 2cylinder Kabota.

How about one of these
Here's the link to the site http://www.alten-dc.com/products.html


G1255D

Powered by Honda GX50
55 Amps / 660 Watts
Made in the USA

Price:

$1,098.00


Specifications

   * Voltage Model: 12 VDC
   * Regulated Charge Voltage: 14V/14.8V (select)
   * Max Amp Output: 55 Amps
   * Voltage Cut Out: 18 VDC
   * Weight: 12kg/26lbs
   * Dimensions (LxWxH): 16.1in x 10.8in x 14.6in
   * Engine: Honda GXH50
   * Max Engine Power: 2.1HP @ 7000 RPM
   * Fuel Capacity: .77L / .2US Gal.
   * Fuel Consumption: ~4 Hour Run Time
   * Fuel Type: Gasoline
   * Oil Capacity: .25L / .26 US Qt.
   * Display: Digital Display Panel
   * Noise Level: 74 dBa @ 7000 RPM
   * Environmental: EPA / CARB
   * Starting: Recoil Start

I don't know
what the real world efficiency is but it may fulfill your needs.

Lloyd

So...to summarize...is there no "reasonable" way I can take, say, 700watts from my little 120v generator, and put it completely or nearly so into a 12v battery?

These guys claim that charging with an automotive type alternator is more efficient than using an AC generator coupled to a charger.

What kind of engine is this?

[BioHazard]

How about one of these
Here's the link to the site http://www.alten-dc.com/products.html

Yeah, I've seen those before. They look very well made, but a little rich for my blood. I guess I'll be trying to build something similar though...

[BioHazard]

While we're talking about it, what would the best charger be that could get the most output from my 800w generator? I have a 6A electronic charger that seems to work fine with it, although I haven't measured the input/output power yet.

Could I do 10 or 20 amps charging without fully loading the generator? Could I do better with a 2500w generator or is that pretty much the same problem?

[BioHazard]

How about an older generator that produces 120/240v at the same time? Would that have the balls to power a modern electronic charger?

[mike90045]

here is a very longish thread
http://www.wind-sun.com/ForumVB/showthread.php?t=10123
about a small inverter (2000W) generator, and what sort of charging load it can feed, and how the power factor of the charger can reduce the actual load capability.